Police conducted spying operations on a string of Labour politicians during the 1990s, covertly monitoring them even after they had been elected to the House of Commons, a whistleblower has revealed.

Peter Francis, a former undercover police officer, said he read secret files on 10 MPs during his 11 years working for the Metropolitan police’s special branch. They include Labour’s current deputy leader, Harriet Harman, the former cabinet minister Peter Hain and the former home secretary Jack Straw.

Francis said he personally collected information on three MPs – Diane Abbott, Jeremy Corbyn and the late Bernie Grant – while he was deployed undercover infiltrating anti-racist groups. He also named Ken Livingstone, the late Tony Benn, Joan Ruddock and Dennis Skinner as having been subjected to special branch intelligence-gathering. The files on all 10 were held by Scotland Yard.

The whistleblower said special branch files were often “very extensive” and typically described the subject’s political beliefs, personal background such as parents, school and finances, and demonstrations they attended. Some contained “some personal and private matters”, Francis added.

None of the British police's spying has been justifiable. All of it threatens democracy. And yet, this is so much worse, raising questions of just what they hoped to achieve by this spying. gathering dirt to curry favour with the government of the day? Or as leverage to use against MPs for their own purposes? Either way, its horrifying. And those responsible for it need to be held to account.

Meanwhile, if the British police are looking for threats to the UK's democracy, maybe they should start by looking in the mirror.